A Failure Estimation Method of Steel Pipe Elbows under In-plane Cyclic Loading

Jeon, Bub-Gyu; Kim, Sung‐Wan; Choi, Hyoung-Suk; Park, Dong-Uk; Kim, Nam-Sik

doi:10.1016/j.net.2016.07.006

Cited by 31 publications

(13 citation statements)

References 4 publications

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“…Specifically, a study was conducted to investigate the limit states of Based on this background, several researchers have conducted studies to determine the seismic safety of piping systems. Specifically, a study was conducted to investigate the limit states of T-joints [5,6], elbows [7,8], etc., which were structurally fragile components of the piping system, through a dynamic cyclic test for the piping. In addition, studies have been carried out to experimentally and analytically investigate the earthquake responses of actual piping subjected to ground shaking [9][10][11].…”

Section: Introductionmentioning

confidence: 99%

Efficient Seismic Fragility Analysis for Large-Scale Piping System Utilizing Bayesian Approach

Kwag

Ryu

2020

Applied Sciences

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In the event of an earthquake, it is essential to accurately assess the seismic fragility of piping systems to ensure the continued safety of society. When evaluating the seismic fragility of a piping system, which is generally a secondary structural system, this should mainly be an integrated model that includes both the primary structural frames and the secondary ones, unlike the primary structural system of a building. Hence, the piping seismic fragility evaluation has an issue in that it takes considerable computational time because numerical analyses must be performed on a relatively complex model. Given this background, the purpose of this study is to propose an efficient piping seismic fragility analysis method by utilizing the existing seismic fragility analysis method and the Bayesian updating concept. In order to verify the validity of the proposed method, it was applied to a building–piping coupled structural system example, and its results were analyzed and compared with the results of the existing method in terms of accuracy and efficiency. As a result, the proposed method showed a similar accuracy compared with the existing method while significantly reducing the numerical cost of nonlinear seismic response analyses necessary for these results.

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Section: Introductionmentioning

confidence: 99%

Efficient Seismic Fragility Analysis for Large-Scale Piping System Utilizing Bayesian Approach

Kwag

Ryu

2020

Applied Sciences

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“…There were several recent studies both experimental and numerical addressing the problem of structural integrity and life of carbon steel elbows under severe loading conditions [6][7][8][9][10][11][12][13][14][15][16]. Fatigue life was mainly considered around 50-300 cycles, as this range is representative of a typical earthquake loading.…”

Section: Introductionmentioning

confidence: 99%

Low Cycle Fatigue Behavior of Elbows with Local Wall Thinning

Harun¹,

Mohammad²,

Kotousov

2020

Metals

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There have been a number of studies concerning the integrity of high-strength carbon steel pipe elbows weakened by local pipe wall thinning, the latter can be typically caused by flow accelerated erosion/corrosion. In particular, the focus of several recent studies was on low cycle fatigue behavior of damaged elbows, mainly, in relation to strength and integrity of piping systems of nuclear power plants subjected to extreme loading conditions, such as earthquake or shutdown. The current paper largely adopts the existing methodology, which was previously developed, and extends it to copper-nickel elbows, which are widely utilized in civil infrastructure in seismically active regions. FE (finite element) studies along with a full-scale testing program were conducted and the outcomes are summarized in this article. The overall conclusion is that the tested elbows with various severity of local wall thinning, which were artificially introduced at different locations, demonstrate a strong resistance against low cycle fatigue loading. In addition, elbows with wall thinning defects possess a significant safety margin against seismic loading. These research outcomes will contribute to the development of strength evaluation procedures and will help to develop more effective maintenance procedures for piping equipment utilized in civil infrastructure.

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“…The damage index of Park and Ang and that of Banon were used to quantitatively express the limit state of a pipe elbow [24]. A study was conducted to define the limit state of a pipe elbow using the damage index based on the dissipated energy [25]. Recently, studies have been conducted to present leakage lines and low-cycle fatigue curves under in-plane cyclic loading conditions of pipe tees [26,27].…”

Section: Introductionmentioning

confidence: 99%

“…Among the various methods of defining the yield point, the tangent intersection (TI) method [32] defines the point at which the tangent of the elastic slope meets the tangent of the plastic slope in the P-D curve as the limit load. This method is well established in the general P-D relationship and was used to calculate the damage index for pipe elbows [20,25]. However, it can be difficult to use if the general slope does not appear in the plastic region.…”

Section: Introductionmentioning

confidence: 99%

Quantitative Limit State Assessment of a 3-Inch Carbon Steel Pipe Tee in a Nuclear Power Plant Using a Damage Index

et al. 2020

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Seismic motions are likely to cause large displacements in nuclear power plants because the main mode of their piping systems is dominated by the low-frequency region. Additionally, large relative displacement may occur in the piping systems because their supports are installed in several places, and each support is subjected to different seismic motions. Therefore, to assess the seismic performance of a piping system, the relative displacement repeated by seismic motions must be considered. In this study, in-plane cyclic loading tests were conducted under various constant amplitudes using test specimens composed of SCH 40 3-inch pipes and a tee in the piping system of a nuclear power plant. Additionally, an attempt was made to quantitatively express the failure criteria using a damage index based on the dissipated energy that used the force–displacement and moment–deformation angle relationships. The failure mode was defined as the leakage caused by a through-wall crack, and the failure criteria were compared and analyzed using the damage index of Park and Ang and that of Banon. Additionally, the method of defining the yield point required to calculate the damage index was examined. It was confirmed that the failure criteria of the SCH 40 3-inch carbon steel pipe tee can be effectively expressed using the damage index.

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A Failure Estimation Method of Steel Pipe Elbows under In-plane Cyclic Loading

Cited by 31 publications

References 4 publications

Efficient Seismic Fragility Analysis for Large-Scale Piping System Utilizing Bayesian Approach

Efficient Seismic Fragility Analysis for Large-Scale Piping System Utilizing Bayesian Approach

Low Cycle Fatigue Behavior of Elbows with Local Wall Thinning

Quantitative Limit State Assessment of a 3-Inch Carbon Steel Pipe Tee in a Nuclear Power Plant Using a Damage Index

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